Telescopic Foundation Screw Pile with Continuously Tapered Pile Body

ABSTRACT

The embodiments provided herein are directed to a telescopic foundation screw piles with continuously tapered pile body that facilitates a faster pile placement speed, less labor and operators, less material, single step operation, low overhead clearance, no excess soils to be removed and hauled away which translates in lower cost and greater ease of use as well as higher load capacity.

FIELD

The embodiments described herein generally relate to a foundation pile, in particular, to a telescopic foundation screw pile with continuously tapered pile body.

BACKGROUND OF THE INVENTION

Foundation piles are widely used (e.g., in the building or other structural fields) for anchoring a component to the ground. Typically, a foundation pile has a retaining portion in the upper region for receiving the anchored component.

A conventional drilled pile can be installed by first drilling a borehole into the ground. Then, a temporary casing is used to seal the borehole through water-bearing or unstable strata overlying suitable stable material. Upon reaching a desired depth, a reinforcing cage is introduced. Then, concrete is poured into the borehole and brought up to the required level. One disadvantage of the conventional drilled pile is that it is labor and material intensive.

An auger-cast pile, often known as a CFA pile, can be formed by drilling into the ground with a hollow stemmed continuous flight auger to a desired depth or degree of resistance. A cement grout mix is then pumped down the stem of the auger. While the cement grout is pumped, the auger is slowly withdrawn, conveying the soil upward along the flights. A shaft of fluid cement grout is formed to ground level. The Auger-cast pile causes minimal disturbance, and is often used for noise and environmentally sensitive sites. However, both the conventional drilled pile and the auger-cast pile are labor intensive, material intensive, unfit for tight spaces, unable to be placed where surcharge loads are present, high overhead clearance and depending on the situation the drilled holes could cave in and create safety concerns. For example, soils removed from the borehole need to be hauled away. In addition, where the ground in a job site is deemed to be contaminated, any soil removed from the ground must be disposed properly, which presenting an additional problem and associated cost.

A more complex system (e.g., STELCOR pile made by the IDEAL Group, 999 Picture Parkway, Webster, N.Y. 14580) whereby a pile is attached to a drill head which is substantially larger than the diameter of the pile itself. The pile is turned together with the drill head by a drilling rig to create a passage in the soil bed through which the pile may pass. A conduit is provided through the center of the pile for water or grout to be pumped down and out the tip of the drill head to either float away debris or anchor the pile in its final resting place in the soil bed. Therefore, no soil is removed during pile installation. Although the system has certain advantages over other known systems, the drilling system is obviously substantially more complex, and therefore more costly than the conventional drilled pile and the auger-cast pile discussed earlier.

Therefore, an improved foundation pile that facilitates a faster pile placement speed, lower cost and greater ease of use as well as higher load capacity is desirable.

BRIEF SUMMARY OF THE EMBODIMENTS

The embodiments provided herein are directed to a telescopic foundation screw piles with continuously tapered pile body that facilitates a faster pile placement speed, less labor and operators, less material, single step operation, low overhead clearance, no excess soils to be removed and hauled away which translates in lower cost and greater ease of use as well as higher load capacity.

Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. It is also intended that the invention is not limited to the details of the example embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the invention, both as to its structure and operation, may be gleaned in part by study of the accompanying figures, in which like reference numerals refer to like parts. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely.

FIG. 1 is a schematic illustration showing an exploded view of an exemplary telescopic foundation screw pile.

FIG. 2 is a schematic illustration showing an enlarged view of a portion near the meeting place between the first section and the second section of the exemplary telescopic foundation screw pile of FIG. 1.

FIG. 3 is a schematic illustration showing a side view of the exemplary telescopic foundation screw pile of FIG. 1.

FIG. 4 is a schematic illustration showing a cross-sectional view taken along A-A of the exemplary telescopic foundation screw pile of FIG. 3.

FIG. 5 is a schematic illustration showing an enlarged view of a portion near the meeting place between the first section and the second section of the exemplary telescopic foundation screw pile of FIG. 4.

FIG. 6 is a schematic illustration showing an enlarged view of a first section of the exemplary telescopic foundation screw pile of FIG. 3.

FIG. 7 is a schematic illustration showing an enlarged view of a second section of the exemplary telescopic foundation screw pile of FIG. 3.

FIG. 8 is a schematic illustration showing an elevation view of another exemplary telescopic foundation screw pile.

FIG. 9 is a schematic illustration showing a front view of the exemplary telescopic foundation screw pile of FIG. 8.

FIG. 10 is a schematic illustration showing a front view of a first section of the exemplary telescopic foundation screw pile of FIG. 8.

FIG. 11 is a schematic illustration showing a cross-sectional view taken along B-B of the exemplary telescopic foundation screw pile of FIG. 10.

FIG. 12 is a schematic illustration showing a front view of a second section of the exemplary telescopic foundation screw pile of FIG. 8.

FIG. 13 is a schematic illustration showing an enlarged view of a portion near the lower end of the second section of FIG. 12.

FIG. 14 is a schematic illustration showing an enlarged view of a portion near the upper end of the second section of FIG. 12.

FIG. 15 is a schematic illustration showing a cross-sectional view taken along C-C of the exemplary telescopic foundation screw pile of FIG. 12.

FIG. 16 is a schematic illustration showing a front view of a first section of another exemplary telescopic foundation screw pile with a plate connection.

FIG. 17 is a schematic illustration showing a side view of a first section of the exemplary telescopic foundation screw pile of FIG. 16.

FIG. 18 is a schematic illustration showing an exploded view of another exemplary telescopic foundation screw pile with a threaded rod connection.

FIG. 19 is a schematic illustration showing a front view of a first section of the exemplary telescopic foundation screw pile of FIG. 18.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic illustration showing an exploded view of an exemplary telescopic foundation screw pile 10. The telescopic foundation screw pile 10 comprises a first section 12, a second section 14, a third section 16, and a fourth section 18. Although the number of sections shown in the exemplary telescopic foundation screw pile 10 comprises four sections, additional sections can be added as desired. In one embodiment, the telescopic foundation screw pile 10 comprises more than four sections. Alternatively, the telescopic foundation screw pile 10 can comprise less than four sections. In one embodiment, the telescopic foundation screw pile 10 comprises three sections. In another embodiment, the telescopic foundation screw pile 10 comprises two sections.

FIG. 2 is a schematic illustration showing an enlarged view of a portion near the meeting place between the first section and the second section of the exemplary telescopic foundation screw pile 10 of FIG. 1. As shown in FIGS. 1 and 2, the first section 12 has a cone-shaped body 20 with a lower end 22 located at the tip side (or the narrower side) and an upper end 24 located at the opposite side (or the wider side) from the lower end 22.

FIG. 3 is a schematic illustration showing a side view of the exemplary telescopic foundation screw pile 10 of FIG. 1. FIG. 4 is a schematic illustration showing a cross-sectional view taken along A-A of the exemplary telescopic foundation screw pile 10 of FIG. 3. The body 20 extends substantially rotationally symmetrically about a longitudinal axis 28 (see FIG. 3), which at the same time defines the longitudinal direction of the body 20. The body 20 is preferably hollow internally.

FIG. 5 is a schematic illustration showing an enlarged view of a portion near the meeting place between the first section and the second section of the exemplary telescopic foundation screw pile 10 of FIG. 4. FIG. 6 is a schematic illustration showing an enlarged view of the first section 12 of the exemplary telescopic foundation screw pile 10 of FIG. 3. In the present embodiment, the cone-shaped body 20 of the first section 12 is continuously tapered from the upper end 24 to the lower end 22. In one embodiment, the degree of taping (i.e., the angle 38 formed between the longitudinal axis 28 and an outer contour 32 running approximately along the longitudinal direction of the body 20) is the same through the whole body 20. Alternatively, the degree of taping can vary through the whole body 20. In a preferable embodiment, at any point of the body 20, the outer diameter at that point is greater than or equal to that at any point lower (i.e., closer to the lower end 22) and less than or equal to that at any point higher (i.e., closer to the upper end 24).

In the present embodiment, the lower end 22 has a round opening 34. In one embodiment, the opening 34 has a radius of less than one inch. Alternatively, the lower end 22 can have a cone-shaped head (not shown). In one embodiment, the head is made of metal. In a further embodiment, the metal is titanium.

In the present embodiment, an annular flange 36 is attached to the upper end 24 of the body 20. In the present embodiment, the flange 36 has a plurality of holes 46 (see FIG. 2) for receiving bolts. In one embodiment, the number of the holes 46 is six.

In the present embodiment, the body 20 of the first section 12 is surrounded by a helical screw thread 48, which extends from the upper end 24 to the lower end 22 over the entire first section 12. In another embodiment, the helical screw thread 48 does not cover the entire first section 12.

In the present embodiment, the helical screw thread 48 is joined to the body 20 via welds. Alternatively, the helical screw thread 48 and the body 20 can be formed together or attached by mechanical means.

In the present embodiment, the body 20, the flange 36, and the helical screw thread 48 are made of metal. In one embodiment, the metal is solid steel.

FIG. 7 is a schematic illustration showing an enlarged view of the second section 14 of the exemplary telescopic foundation screw pile 10 of FIG. 3. In the present embodiment, the second section 14 has a frustum-shaped body 50 with a lower end 52 and an upper end 54. The body 50 extends substantially rotationally symmetrically about the longitudinal axis 28, which at the same time defines the longitudinal direction of the body 50.

The body 50 is preferably hollow internally. In the present embodiment, the body 50 is continuously tapered from the upper end 54 to the lower end 52. In one embodiment, the degree of taping (i.e., the angle 60 formed between the longitudinal axis 28 and an outer contour 62 running approximately along the longitudinal direction of the body 50) is the same through the whole body 50. Alternatively, the degree of taping can vary through the whole body 50. In a preferable embodiment, at any point of the body 50, the outer diameter at that point is greater than or equal to that at any point lower (i.e., closer to the lower end 52) and less than or equal to that at any point higher (i.e., closer to the upper end 54).

In the present embodiment, an annular lower flange 66 is attached to the lower end 52 of the body 50. In the present embodiment, the lower flange 66 has a plurality of holes 78 (see FIG. 2) for receiving bolts. In the present embodiment, the number of the holes 78 is six. In one embodiment, the lower flange 66 is joined to the body 50 via welds. Alternatively, the lower flange 66 and the body 50 can be formed together or attached by mechanical means.

In the present embodiment, an annular upper flange 80 is attached to the upper end 54 of the body 50. In the present embodiment, the upper flange 80 has a plurality of holes (not shown) for receiving bolts. In the present embodiment, the upper flange 80 has additional slots (not shown) for facilitating the connection of the pile 12 to a pile driving equipment (not shown) if the second section 14 is the last section of the pile 10.

In the present embodiment, the body 50 of the second section 14 is surrounded by a helical screw thread 94, which extends from the upper end 54 to the lower end 52 over the entire second section 14. In another embodiment, the helical screw thread 94 does not extends over the entire second section 14.

In the present embodiment, the helical screw thread 94 is joined to the body 50 via welds. Alternatively, the helical screw thread 94 and the body 50 can be formed together or attached by mechanical means.

In the present embodiment, the body 50, the flanges 66, 80 and the helical screw thread 94 are made of metal. In one embodiment, the metal is solid steel.

In the present embodiment, the first section 12 and the second section 14 are merged by aligning the flange 36 of the first section 12 with the lower flange 66 of the second section 14. Then, a fixing mechanism is used to merge the first section 12 with the second section 14. In one embodiment, bolting is used to merge the first section 12 with the second section 14. After the merge of the first section 12 and the second section 14, the outer contour of the merged unit are preferably smoothly aligned so that a continuously taper outer contour is still formed from the upper end 54 of the second section 14 all the way to the lower end 22 of the first section 12.

The third section 16 and the fourth section 18 can have similar structure as that of the second section 12 except that they have different lateral dimension so as to keep a continuously taper outer contour of the telescopic foundation screw pile 10 when they are merged with the first section 12 and the second section 14.

Referring back to FIGS. 3 and 4, the second section 14 and the third section 16 can be merged by aligning the upper flange 80 of the second section 14 with a lower flange 72 of the third section 16. Then, a fixing mechanism can be used to merge the second section 14 and the third section 16. Similarly, the third section 16 and the fourth section 18 can be merged by aligning an upper flange 76 of the third section 16 with a lower flange 98 of the fourth section 18. Then, a fixing mechanism can be used to merge the third section 16 with the fourth section 18. After the merge of all sections 12, 14, 16, 18, the outer contour of the telescopic foundation screw pile 10 forms a continuously taper outer contour from the upper end 96 of the fourth section 18 all the way to the lower end 22 of the first section 12.

Although the embodiments described earlier employ holes on the flanges 36, 66, 80, 72, 76, 98 for bolt connection, other configurations can also be used for connecting adjacent sections. For example, instead of the bolted connection, a plate connection (see FIGS. 16, 17) or a threaded rod connection (see FIGS. 18, 19) can be used. A more detailed description on the plate connection and the threaded rod connection will be provided hereafter.

FIG. 8 is a schematic illustration showing an elevation view of another exemplary telescopic foundation screw pile 110. FIG. 9 is a schematic illustration showing a front view of the exemplary telescopic foundation screw pile 110 of FIG. 8. The telescopic foundation screw pile 110 comprises a first section 112, a second section 114, a third section 116, and a fourth section 118. Although the number of sections shown in the exemplary telescopic foundation screw pile 110 comprises four sections, additional sections can be added as desired. In one embodiment, the telescopic foundation screw pile 110 comprises more than four sections. Alternatively, the telescopic foundation screw pile 110 can comprise less than four sections. In one embodiment, the telescopic foundation screw pile 110 comprises three sections. In another embodiment, the telescopic foundation screw pile 110 comprises two sections. In one embodiment, the first section 112 can be a standalone pile.

FIG. 10 is a schematic illustration showing a front view of the first section 112 of the exemplary telescopic foundation screw pile 110 of FIG. 8. The first section 112 has a cone-shaped body 120 with a lower portion 121, a middle portion 123 and an upper portion 125. The lower portion 121 and the middle portion 123 intersect at a joint place 127. The middle portion 123 and the upper portion 125 intersect at a joint place 129. A lower end 122 is located at the tip side (or the narrower side) of the lower portion 121 and an upper end 124 is located at the opposite side (or the wider side) from the lower end 122. The three portions 121, 123 and 125 are shown for reference purpose. In the present embodiment, the body 120 is fabricated from one continuous tube and there can be no joints or welds on the tube.

The body 120 extends substantially rotationally symmetrically about a longitudinal axis 128 (see FIG. 9), which at the same time defines the longitudinal direction of the body 120. The body 120 is preferably hollow internally. In the present embodiment, the lower portion 121 is continuously tapered from the joint place 127 to the lower end 122; the middle portion 123 is continuously tapered from joint place 129 to joint place 127. In the present embodiment, the upper portion 125 maintains a constant diameter so that it can be placed in a spindle of a swaging equipment. Alternatively, the upper portion 125 can be continuously tapered from the upper end 124 to joint place 129. Therefore, the body 120 of the first section 112 is continuously tapered from the upper end 124 to the lower end 122.

In the present embodiment, the degree of taping (i.e., the angle formed between the longitudinal axis 128 and an outer contour running approximately along the longitudinal direction of the body 120) are different among portions 121, 123 and 125. In one embodiment, the degree of taping of the lower portion 121 is greater than that of the middle portion 123. In addition, the degree of taping of the middle portion 123 is greater than that of the upper portion 125. In a preferable embodiment, at any point of the body 120, the outer diameter at that point is greater than or equal to that at any point lower (i.e., closer to the lower end 122) and less than or equal to that at any point higher (i.e., closer to the upper end 124). Alternatively the degree of taping can be the same through the whole body 120.

In the present embodiment, the lower end 122 has a round opening 134. In one embodiment, the opening 134 has a radius of less than one inch. Alternatively, the lower end 122 can have a cone-shaped head (not shown). In one embodiment, the head is made of metal. In a further embodiment, the metal is stainless steel. Alternatively, the metal is aluminum or titanium.

In one embodiment, the length in the longitudinal direction of the lower portion 121 is 12 inches; the length in the longitudinal direction of the middle portion 123 is 52 inches; and the length in the longitudinal direction of the upper portion 125 is 8 inches.

In one embodiment, the outer diameter at the lower end 122 is 1.2 inches; the outer diameter at the joint place 127 is 3 inches; the outer diameter at the joint place 129 is 5 inches; and the outer diameter at the upper end 124 is 5 inches.

In one embodiment, the degree of taping of the lower portion 121 is 4.3°. In one embodiment, the degree of taping of the middle portion 123 is 1.1°.

FIG. 11 is a schematic illustration showing a cross-sectional view taken along B-B of the first section 112 of FIG. 10. In the present embodiment, an annular flange 136 is attached to the upper end 124 of the body 120. In one embodiment, the annular flange 136 has a thickness of 0.5 inches. The flange 136 has an outer diameter 142 which is greater than the outer diameter of the body 120 at the upper end 124. In one embodiment, the outer diameter of the body 120 at the upper end 124 is 5.8 inches. In one embodiment, the outer diameter 142 of the flange 136 is 8.1 inches.

In the present embodiment, the flange 136 has a plurality of holes 146 for receiving bolts. In one embodiment, the number of the holes is six. In one embodiment, the flange 136 is joined to the body 120 via welds. Alternatively, the flange 136 and the body 120 can be formed together or attached by mechanical means.

In the present embodiment, the body 120 of the first section 112 is surrounded by a helical screw thread 148, which extends from joint place 129 to joint place 127 over the entire middle portion 123. Alternatively, the helical screw thread 148 can extends from the upper end to the lower end 122 over the entire body 120.

In the present embodiment, the helical screw thread 148 is joined to the body 120 via welds. Alternatively, the helical screw thread 148 and the body 120 can be formed together or attached by mechanical means.

In the present embodiment, the body 120, the flange 136, and the helical screw thread 148 are made of metal. In one embodiment, the metal is solid steel.

FIG. 12 is a schematic illustration showing a front view of a second section 114 of the exemplary telescopic foundation screw pile 110 of FIG. 8. The second section 114 has a frustum-shaped body 150 with a lower portion 151, a middle portion 153 and an upper portion 155. The lower portion 151 and the middle portion 153 intersect at a joint place 157. The middle portion 153 and the upper portion 155 intersect at a joint place 159. A lower end 152 is located at the narrower side of the lower portion 151 and an upper end 124 is located at the opposite side (or the wider side) from the lower end 152. The three portions 151, 153 and 155 are shown for reference purpose. In the present embodiment, the body 150 is fabricated from one continuous tube and there can be no joints or welds on the tube.

In the present embodiment, the body 150 extends substantially rotationally symmetrically about a longitudinal axis (not shown), which at the same time defines the longitudinal direction of the body 150. The body 150 is preferably hollow internally.

In the present embodiment, the lower portion 151 is continuously tapered from the joint place 157 to the lower end 152; the middle portion 153 is continuously tapered from joint place 159 to joint place 157; and the upper portion 155 is continuously tapered from the upper end 154 to joint place 159. In one embodiment, the body 150 of the second section 114 is continuously tapered from the upper end 154 to the lower end 152.

In the present embodiment, the degree of taping (i.e., the angle formed between the longitudinal axis 128 and an outer contour running approximately along the longitudinal direction of the body 120) are different among portions 151, 153 and 155. In one embodiment, the degree of taping of the lower portion 151 is greater than that of the middle portion 153. In addition, the degree of taping of the middle portion 153 is greater than that of the upper portion 155. In a preferable embodiment, at any point of the body 150, the outer diameter at that point is greater than or equal to that at any point lower (i.e., closer to the lower end 152) and less than or equal to that at any point higher (i.e., closer to the upper end 154). Alternatively the degree of taping can be the same through the whole body 150.

In one embodiment, the length in the longitudinal direction of the lower portion 151 is 8 inches; the length in the longitudinal direction of the middle portion 153 is 52 inches; and the length in the longitudinal direction of the upper portion 155 is 8 inches.

In one embodiment, the outer diameter at the lower end 152 is 5 inches; the outer diameter at the joint place 157 is 5.3 inches; the outer diameter at the joint place 159 is 7 inches; and the outer diameter at the upper end 154 is 7 inches.

FIG. 13 is a schematic illustration showing an enlarged view of a portion near the lower end of the second section 114 of FIG. 12. In the present embodiment, an annular lower flange 166 is attached to the lower end 152 of the body 150. In one embodiment, the lower flange 166 has a thickness 168 of 0.6 inches. The lower flange 166 has an outer diameter 174 which is greater than the outer diameter 170 of the body 150 at the lower end 152. In the present embodiment, the size of the outer diameter 174 of the lower flange 166 of the second section 114 is substantially the same as the size of the outer diameter 142 of the flange 136 of the first section 112. In one embodiment, the outer diameter 174 of the flange 166 is 8.1 inches.

In the present embodiment, the lower flange 166 has a plurality of holes 178 for receiving bolts. In one embodiment, the number of the holes 178 is six. In the present embodiment, the lower flange 166 is joined to the body 150 via welds. Alternatively, the lower flange 166 and the body 150 can be formed together or attached by mechanical means.

FIG. 14 is a schematic illustration showing an enlarged view of a portion near the upper end of the second section 114 of FIG. 12. In the present embodiment, an annular upper flange 180 is attached to the upper end 154 of the body 150. In one embodiment, the upper flange 180 has a thickness 182 of 0.6 inches. The upper flange 180 has an outer diameter 188 which is greater than the outer diameter of the body 150 at the upper end 154. In one embodiment, the outer diameter 188 of the upper flange 180 is 10.1 inches.

FIG. 15 is a schematic illustration showing a cross-sectional view taken along C-C of the exemplary telescopic foundation screw pile 112 of FIG. 12. In the present embodiment, the upper flange 180 has a plurality of holes 192 for receiving bolts. In one embodiment, the number of the holes 192 is ten. In one embodiment, the diameter of the holes 192 is 0.7 inches. The upper flange 180 has additional slots 187 for facilitating the connection of the pile 114 to a pile driving equipment (not shown). In one embodiment, the upper flange 180 is joined to the body 150 via welds. Alternatively, the upper flange 180 and the body 150 can be formed together or attached by mechanical means.

In the present embodiment, the body 150 of the second section 114 is surrounded by a helical screw thread 194, which extends from joint place 159 to joint place 157 over the entire middle portion 153. Alternatively, the helical screw thread 194 can extends from the upper end 154 to the lower end 152 over the entire body 150 of the second section 114.

In one embodiment, the helical screw thread 194 is joined to the body 150 via welds. Alternatively, the helical screw thread 194 and the body 150 can be formed together or attached by mechanical means.

In one embodiment, the body 150, the flanges 166, 180 and the helical screw thread 194 are made of metal. In a further embodiment, the metal is stainless steel. Alternatively, the metal is aluminum or titanium.

In the present embodiment, the first section 112 and the second section 114 are merged by aligning the flange 136 of the first section 112 with the lower flange 166 of the second section 114. Then, a fixing mechanism is used to merge the first section 112 with the second section 114. In one embodiment, bolting is used to merge the first section 112 with the second section 114. After the merge of the first section 112 and the second section 114, the outer contour of the merged unit are preferably smoothly aligned so that a continuously taper outer contour is still formed from the upper end 154 of the second section 114 all the way to the lower end 122 of the first section 112.

The third section 116 and the fourth section 118 can have similar structure as the second section 114 except that they have different lateral dimension so as to keep a continuously taper outer contour of the telescopic foundation screw pile 110 when they are merged with the first section 112 and the second section 114

Referring also to FIG. 8, the second section 114 and the third section 116 can be merged by aligning the upper flange 180 of the second section 114 with the lower flange 172 of the third section 116. Then, a fixing mechanism can be used to merge the second section 114 and the third section 116. Similarly, the third section 116 and the fourth section 118 can be merged by aligning the upper flange 176 of the third section 116 with the lower flange 198 of the fourth section 118. Then, a fixing mechanism can be used to merge the third section 116 with the fourth section 118. After the merge of all sections 112, 114, 116, 118, the outer contour of the telescopic foundation screw pile 110 forms a continuously taper outer contour from the upper end 196 of the fourth section 118 all the way to the lower end 122 of the first section 112.

Although the embodiments described earlier employ holes on the flanges 136, 166, 180, 172, 176, 198 for bolt connection, other configurations can also be used for connecting adjacent sections. For example, instead of the bolted connection, a plate connection (see FIGS. 16, 17) or a threaded rod connection (see FIGS. 18, 19) can be used. A more detailed description on the plate connection and the threaded rod connection will be provided hereafter.

The manufacturing process for making the telescopic foundation screw piles 10 and 110 will be described in further details hereafter. Tubes of different diameter can be selected as fabricated tubes. For example, tubes of HSS “Hollow Structural Steel” ASTM A-500 Grade A or B can be used. For example, a 5 inch diameter round tube can be selected for the first section; a 7 inch diameter round tube can be selected for the second section, etc. Then the tubes can be cut into desired section length. Then, a swaging process can be performed on the sectioned tube to reduce its diameter to form a continuously taper tube. For example, the 7 inch diameter round tube for the second section can be swaged to have a diameter of 7 inch diameter at the upper end and a 5 inch diameter at the lower end with a continuously taping. The swaging process can be either hot swaging or cold swaging.

The connection between sections can be performed by a flange to flange bolted connection as described previously in connection with the telescopic foundation screw piles 10 and 110. Individual flanges can first be fabricated to their corresponding geometry in a factory. Flanges can then be welded to the sections at the factory. The first section has one flange at its upper end. The other sections have two flanges, one at the lower end and one at the upper end. Then, the sections are installed in the field by bolting the corresponding flanges from connecting sections. The upper flange of the last (the up most) section can have slots for connecting the pile to a pile driving equipment.

Alternatively, the connection between sections can be performed by a plate connection. FIG. 16 is a schematic illustration showing a front view of a first section 212 of another exemplary telescopic foundation screw pile 210 with a plate connection. FIG. 17 is a schematic illustration showing a side view of the first section 212 of the exemplary telescopic foundation screw pile of FIG. 16. Although only the first section 212 is shown herein, the telescopic foundation screw pile 210 can comprise multiple sections similarly to that of the telescopic foundation screw pile 10 or 110. In addition, the configuration of the telescopic foundation screw pile 210 can be similar to that of the telescopic foundation screw pile 10 or 110 except for the connection scheme. Referring to FIGS. 16 and 17, a plate 220 with holes 224 can be fabricated in the factory and welded to the sections. Preferably, the plate 220 is welded only on the top portion 222 of each of the individual section. The bottom portion of each section (except the first section) has holes on the body. The corresponding sections can be connected via bolts with positions predetermined in the sections. Because there is no extension protruded out of the body as the flange has, the plate connection is preferred for installation in soils that the use of flanges would cause difficulty in penetration. The upper portion of the last section can have slots for connecting the pile to a pile driving equipment.

Alternatively, the connection between sections can be performed by a threaded rod connection. FIG. 18 is a schematic illustration showing an exploded view of another exemplary telescopic foundation screw pile 310 with a threaded rod connection. FIG. 19 is a schematic illustration showing a front view of a first section 312 of the exemplary telescopic foundation screw pile 310 of FIG. 18. Although only the first section 312 and the second section 314 are shown herein, the telescopic foundation screw pile 310 can comprise multiple sections similarly to that of the telescopic foundation screw pile 10 or 110. In addition, the configuration of the telescopic foundation screw pile 310 can be similar to that of the telescopic foundation screw pile 10 or 110 except for the connection scheme. Referring to FIGS. 18 and 19, a rod 320 with threads (not shown) can be machined with a flange 330 in the factory. The flange 330 is preferably located at the middle portion of the rod 320 so that threads are on both ends of the rod 320. The inner surface 326, 328 of the top portion and bottom portion (except for the first section) of each section can be threaded in the factory. Field installation can be done by screwing the sections 312, 314 to be connected by using the threaded rod 320. Because the threaded rod connection has a flange 330 that typically does not protrude more than a quarter inch from the body of tube sections 312, 314, the threaded rod connection would not cause much difficulty in pile penetration. The upper portion of the last section can have slots for connecting the pile to a pile driving equipment.

Although the flange to flange bolted connection, the plate connection, and the threaded rod connection described hereinbefore are used mutually exclusive in different embodiments, a pile can be fabricated and installed with more than one connection schemes if desired.

The telescopic foundation screw piles 10, 110, 210, 310 described herein have several advantages. First, there is no requirement of pre-drill or digging to the soils for installation of the telescopic piles. Therefore, there is no potential spoils or cross contamination. In addition, there is no requirement of refilling of concrete or grout, resulting in a fast, simple, low cost and ease of use installation processing.

In addition, the use of telescopic piles with variable number of sections, which can be flexibly chosen, based on the desired depth of the foundation, can reduce the cost of materials. In addition, energy for drilling can be reduced.

In addition, the continuously taping outer contour of the telescopic piles provides a uniformly lateral pressure to the soils in terms of the depth of the foundation, resulting in an improved soil density around the installed telescopic piles so as to achieve a higher load capacity.

In addition, the continuously taping outer contour of the telescopic piles provides an increased skin friction. Nordlund developed a method of calculating skin friction based on field observations and results of several pile load tests in cohesionless soils. Several pile types were used, including timber, H type steel, pipe, monotube, etc. The method accounts for pile taper and for differences in pile materials. Nordlund indicates that the unit skin friction is increased by a factor of at least 1.5 for an angle of taper of 0.5 degrees (approximately 1%). (See page 119, M. J. Tomlinson, Pile Design and Construction Practice, fourth edition, Tayler and Francis, Oxon, UK, 1994.)

While the invention has been described in connection with specific examples and various embodiments, it should be readily understood by those skilled in the art that many modifications and adaptations of the invention described herein are possible without departure from the spirit and scope of the invention as claimed hereinafter. Thus, it is to be clearly understood that this application is made only by way of example and not as a limitation on the scope of the invention claimed below. The description is intended to cover any variations, uses or adaptation of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within the known and customary practice within the art to which the invention pertains. 

What is claimed is:
 1. A telescopic foundation screw pile comprising: a first section having a lower end, an upper end, and a continuously tapering body surrounding by a helical screw thread; and a second section having a lower end, an upper end, and a continuously tapering body surrounding by a helical screw thread, wherein the first section and the second section form a continuously tapering outer contour from the upper end of the second section all the way to the lower end of the first section.
 2. The telescopic foundation screw pile of claim 1, wherein the helical screw thread of the first section covers a portion of the body.
 3. The telescopic foundation screw pile of claim 1, wherein the helical screw thread of the second section covers a portion of the body.
 4. The telescopic foundation screw pile of claim 1, wherein the first section has a flange attached to the upper end.
 5. The telescopic foundation screw pile of claim 1, wherein the second section has a lower flange attached to the lower end and an upper flange attached to the upper end.
 6. The telescopic foundation screw pile of claim 5, wherein the flange of the first section is merged with the lower flange of the second section.
 7. The telescopic foundation screw pile of claim 6, wherein the flange of the first section and the lower flange of the second section is merged by bolting.
 8. The telescopic foundation screw pile of claim 6, further comprising a third section having a lower end, an upper end, and a continuously tapering body surrounding by a helical screw thread, wherein the third section has a lower flange attached to the lower end and an upper flange attached to the upper end, and wherein the upper flange of the second section is merged with the lower flange of the third section.
 9. The telescopic foundation screw pile of claim 8, further comprising a fourth section having a lower end, an upper end, and a continuously tapering body surrounding by a helical screw thread, wherein the fourth section has a lower flange attached to the lower end and an upper flange attached to the upper end, and wherein the upper flange of the third section is merged with the lower flange of the fourth section.
 10. A telescopic foundation screw pile comprising a plurality of sections connected together to form a single unit, wherein the unit has a continuously tapering body surrounding by a plurality of helical screw threads.
 11. The telescopic foundation screw pile of claim 10, wherein the number of the plurality of sections is four. 